1. Field of the Invention
The present invention is related to an apparatus or device for engaging the internal surface of a conduit or pipe to provide a leakproof interengagement and prevent the flow of a fluid (e.g. liquids, etc.) through the conduit or pipe. More specifically, the present invention provides for an apparatus or device and method for sealing the interchange section of a meter proving assembly to prevent the flow of liquids therethrough. The sealing apparatus of the present invention provides an integrity seal between the inlet and outlet of a unidirect prover (i.e. a meter prover) to insure that all the product metered goes through the unidirect prover and none leaks through the seals.
2. Description of the Prior Art
A mechanical conventional displacement meter prover operates on a common principal, namely: the displacement of a known volume of liquid in a calibrated section of pipe between two signaling detectors by means of a displacer (sphere) which is driven along the pipe by the pressure gradient in the liquid stream being metered. Simultaneously, the corresponding meter volume is being recorded or indicated and the ratio between the known volume in the prover and the meter's indicated volume is called the meter factor.
The mechanical displacement meter prover is a critical element in liquid metering installations because the prover is the volumetric standard against which the flow of meters are calibrated. The prover and all associated piping is an area where high reliability is very important, and the accuracy of the prover itself is dependent upon the resolution of the detector switches and meters, steady-state flow conditions and the sealing factor to determine the volume. For an accurate proving run, it is essential that all the fluid passing through the meter also pass through the prover barrel. Hence, it is essential that a positive seal (Interchange Seal) be provided on the system as liquid must not by-pass the prover when the displacer (sphere) is traveling between the detector switches.
Pipe provers are the most common method for proving metering systems. Volumetric prover tanks and the master-meter-method are used regularly, although a much greater accuracy is gained with pipe provers in the capability of determining the performance of the meters and volume thruput.
A common pipe prover is known as a "unidirect prover". A unidirect prover is one in which a sealing assembly allows the sphere to travel in a pipe section in one direction only, to displace a predetermined volume between two known points in the cylinder. These points are indicated by the electrical indicators. The sphere travels one way through the prover and returns from the receiving side back to the launching side through a uni-directional interchange. The sealing assembly is an integrity seal between the inlet and outlet of the unidirect prover to insure that all the product metered goes through the prover and none leaks through the seals. There is a pressure differential switch installed between the two seals to prove the integrity of the seal. The design of this interchange is very cost effective as it illiminates the need for a diverter valve.
It is therefore important that the sealing assembly within the interchange be reliable in order to obtain an accurate proving run. An inaccurate proving run is costly. The following prior art sealing assemblies do not provide the necessary features to make a successful and/or effective seal for meter proving purposes:
U.S. Pat. No. 100,115--titled: IMPROVEMENT IN TUBE-STOPPER, to W. Brown; PA0 U.S. Pat. No. 2,374,947--titled: HIGH PRESSURE TEST PLUG, to Nicholson; PA0 U.S. Pat. No. 3,006,680--titled PIPE HANDLING APPARATUS. FOR USE IN AND ABOUT A DERRICK, to Gregory; PA0 U.S. Pat. No. 4,303,101--titled END PLUG ASSEMBLY FOR SEWER PIPE, to Tholen; PA0 U.S. Pat. No. 4,381,800--titled PIPE TESTING PLUG to Leslie PA0 U.S. Pat. No. 5,297,691--titled CLOSURE PLUG AND METHODS OF EMPLOYING THE SAME TO MAINTAIN A FIRE-RATED BARRIER, to Bottcher;
U.S. Pat. No. 100,115 to Brown discloses an improvement to a tube-stopper. The improvement consists in a certain combination of a bolt and nut with reversed cones or truncated devices, and a packaging ring, all arranged so that on screwing up the nut, the cones are made to act upon the ring from opposite sides. Such opposed actions on the ring expands or spreads it to thereby cause the ring to close or stop the tube. U.S. Pat. No. 100,115 also discloses in combination with the immediate foregoing, a chamber arranged between the truncated ends of the cones, filled with red lead or any other suitable cement, whereby upon screwing up the nut, the cones are made to force out the cement in order to affect a more perfect sealing or closing of the stopper.
U.S. Pat. No. 2,374,947 to Nicholson discloses a high pressure plug which is designed for use in testing types, tubes or similar tubular objects. The test plug is disclosed as having expanding sections adjustable with respect to each other, and so constructed that when the sections are moved towards each other, the rubber sleeve surrounding the sections and forming a part of the plug, will expand into close engagement with the pipe or tube under test.
U.S. Pat. No. 3,006,680 to Gregory teaches a pipe apparatus for use in and about a derrick. U.S. Pat. No. 3,006,680 more particularly discloses a wet plug which may be used in conjunction with a stand of well pipe or tubing. The wet plug includes a packer member, a cam mechanism disposed above the packer member, and a valve member arranged above the cam mechanism. The packer member is taught as being formed of resilient material such that the cam mechanism may expand the packer member radially outwardly to its pipe sealing position.
U.S. Pat. No. 4,303,101 to Tholen discloses a reusable plug assembly for a pipe, more particularly a sewer pipe. The end plug assembly includes an external plate seal member for bearing against an end portion of a pipe. The external end plate seal member has an inwardly extending sleeve with a flared portion arranged and constructed to have a line engagement with the internal surface of the pipe. The end pipe assembly further includes a wedge member which is to be drawn inwardly of the sleeve, and an external screw member for drawing the wedge into the sleeve and compressing the plate seal against the end of the pipe to provide a simultaneous sealing engagement with the internal surface of the pipe.
U.S. Pat. No. 4,381,800 to Leslie discloses a pipe stopper, more particularly a high pressure pipe tester plug which when inserted into a pipe is capable of isolating a particular joint such as a weld for hydrostatic testing. The plug includes a stem having a threaded section, a smooth section and terminating in a fixed tapered washer. A plurality of grip segments are arranged cylindrically about the stem and have tapered openings at each end. An annular floating mandrel is positioned about the stem for cooperation with the top end of the grip segments. The floating mandrel includes an upper retaining section, an adjacent cylindrical section and a tapered entry section. An O-ring is positioned in an internal recess in the floating mandrel and is adapted for sealable engagement with the smooth section of the stem. A ring-shaped seal, rectangular in cross section, is positioned about the cylindrical section of the floating mandrel and retained by the upper retaining section thereof. A nut threadably engages the threaded portion of the stem and, when tightened, forces the floating mandrel into the top end of the grip segments causing the O-ring to sealably engage the stem and the ring-shaped seal to engage the pipe interior to isolate the joint for testing.
U.S. Pat. No. 5,297,691 to Bottcher discloses a closure plug. The closure plug comprises opposing frusto-conical sections to apply lateral forces to axially compress and radially expand an O-ring to seal the plug within an opening through a fire rated barrier to support or enclose insulating materials which may fill all or part of the opening through the barrier.
Therefore, what is needed and what has been invented is an improved apparatus that is capable of sealing off the insides of a pipe to prevent the flow of fluids therethrough. What is further needed and what has been further invented is a method for plugging a pipe, more particularly for plugging the interchange section of a unidirect prover.